Small diameter metal tubing is widely used for the transmission of fluids and fluid pressures from one device to another for the operation and control of numerous machines and processes. In connecting such devices the tubing is bent to conform to contours of equipment and structures. In bending tubing constraint must be placed on the side of the tubing to prevent flattening or kinking which would weaken the tube and interfere with the flow of fluid. Various kinds of benders are used for this application.
It has been know to bend tubing by wrapping the tubing around a form of the desired bend angle. It is also known that if the tubing is bent too sharply around a form, it will collapse upon itself and reduce its internal cross-section, thus reducing the tubing's effectiveness in carrying fluid or fluid pressure.
It is known to use tools that are effective in preventing kinking when bending tubing. Most such tools provide a guide for feeding the tubing through a bending form. Most of these tools are alike in that they produce the bend by swagging the tube in a circular form to the desired angle of bend; they differ in the means of rotating the form against the guide or shoe and in the method of inserting and removing the tube after bending.
The following patents are the prior art closest to the present invention known to the inventor:
U.S. Pat. No. 2,719,561--Bizak PA1 U.S. Pat. No. 3,448,602--Stanley PA1 U.S. Pat. No. 3,662,580--Power PA1 U.S. Pat. No. 3,735,621--Dodge PA1 U.S. Pat. No. 3,785,190--Schall